stackchk.h File Reference

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Data Structures
struct	StackchkStruct

Macros
#define	STACKCHKFILLBYTE   (0x5A)
	The Byte Pattern used for Filling. More...

Functions
void	Stackchk (void)
	Fills the stackchk Struct. More...

Variables
StackchkStruct	stackchk
	Stores the results of Stackchk(). Always call Stackchk() before using this values! More...

Macro Definition Documentation

STACKCHKFILLBYTE

#define STACKCHKFILLBYTE   (0x5A)

The Byte Pattern used for Filling.

Function Documentation

Stackchk()

void Stackchk

(

void

)

Fills the stackchk Struct.

It walks through the free RAM to find the probable end of the heap and the beginning of the stack. Note that there is no guarantee that heap nor stack cannot grow more than this but it can give you an idea of how many spare bytes you have before heap and stack collide.
Heap end is detected if four consecutive fill bytes are found. In extreme cases this may happen inside the heap as well. Also, the last bytes on the stack may accidentally be the same than the fill byte and the real stack size would not be correctly found. You might want to use different fill bytes to get more exact results. You must decide yourself ho probable the fill byte is in your application.
You can calculate the reserve before heap and stack would collide as

stackchk.stackmin-stackchk.heapmax-1

References __bss_end, StackchkStruct::heapmax, stackchk, STACKCHKFILLBYTE, and StackchkStruct::stackmin.

Referenced by DoTflags(), and ShowScreen().

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Variable Documentation

stackchk

StackchkStruct stackchk

Stores the results of Stackchk(). Always call Stackchk() before using this values!

Referenced by ShowScreen(), Stackchk(), and StackchkFill().